Dysregulation of VEGF RNA Stability in Amyotrophic Lateral Sclerosis

描述(申请人提供)：项目摘要：肌萎缩侧索硬化症(ALS)是一种破坏性疾病。最近的证据表明，血管内皮生长因子(VEGF)是细胞应激过程中神经保护的关键因素，其在神经组织中的下调导致运动神经元加速死亡。促进血管内皮生长因子上调以应对细胞压力的一个分子途径是RNA稳定。然而，当细胞暴露在压力下，如低氧暴露、氧化代谢产物或炎性细胞因子暴露时，血管内皮生长因子转录本变得稳定，导致表达增强和随后的神经保护。在我们对ALS超氧化物歧化酶(SOD1)突变小鼠模型的初步研究中，我们观察到与VEGFRNA不稳定有关的VEGFmRNA水平显著降低。在这个提案中，我们将检验两个密切相关的假设：1)在突变SOD1的存在下，血管内皮生长因子的失稳和下调是由于RNA稳定剂HUR的功能障碍造成的。2)星形胶质细胞和神经元之间的细胞间信号转导触发了异常的血管内皮生长因子基因稳定反应。为了检验这些假说，本文提出了三个具体目标。首先，我们将研究细胞质HUR易位和突变型SOD1在血管内皮生长因子mRNA失稳和下调中的作用。其次，我们将分析突变的SOD1蛋白、HUR和与VEGF3‘UTR相关的RNP复合体之间的相互作用，以确定突变的SOD1为什么对VEGFRNA的加工产生负面影响。第三，我们将在运动神经元样细胞和表达野生型或突变型SOD1的神经胶质细胞的共培养模型中，研究突变型SOD1诱导的血管内皮生长因子失稳的影响。相关性：这项提议有望阐明在突变的SOD1小鼠中血管内皮生长因子下调的机制，并提供ALS病理的两个重要方面之间的可能的分子联系：血管内皮生长因子和SOD1突变蛋白。对这一联系的进一步研究可以为ALS的发病机制提供洞察力，并最终为这种目前无法治愈的疾病提供治疗干预。

DESCRIPTION (provided by applicant): Project Summary: Amyotrophic lateral sclerosis (ALS) is a devastating disease. Recent evidence indicates that vascular endothelial growth factor (VEGF) is a critical element for neuroprotection during cellular stress, and that its down-regulation in neural tissues contributes to accelerated motor neuron death. One molecular pathway that promotes VEGF up-regulation in response to cellular stress is RNA stabilization. When cells are exposed to stress, such as hypoxic exposure, oxidative metabolites, or inflammatory cytokine exposure, however, the VEGF transcript becomes stabilized, resulting in enhanced expression and subsequent neuroprotection. In our preliminary studies with the superoxide dismutase (SOD1) mutant mouse model of ALS, we have observed a marked diminution of VEGF mRNA levels that is linked to VEGF RNA destabilization. In this proposal, we will test two closely related hypotheses: 1) VEGF destabilization and down-regulation is due to dysfunction of the RNA stabilizer, HuR, in the presence of mutant SOD1. 2) Intercellular signaling between astrocytes and neurons triggers the aberrant VEGF mRNA stabilization response. Three specific aims are proposed to test these hypotheses. First, we will investigate the role of cytoplasmic HuR translocation and mutant SOD1 in the destabilization and down-regulation of VEGF mRNA. Second, we will analyze the interaction between mutant SOD1 proteins, HuR and the RNP complex associated with the VEGF 3'UTR to determine why mutant SOD1 negatively affects VEGF RNA processing. Third, we will investigate the impact of the mutant SOD1-induced VEGF destabilization in a co-culture model of motor neuron-like cells and glial cells that express wild-type or mutant SOD1. Relevance: This proposal has the promise to elucidate the mechanism by which VEGF is down regulated in mutant SOD1 mice, and to provide a possible molecular link between two important aspects of ALS pathology: VEGF and SOD1 mutant proteins. Further investigation of this link could provide insight into the pathogenesis of ALS, and ultimately therapeutic intervention for this currently incurable disorder.